This invention relates to a servo-controlled traverse mechanism for a winder, particularly a textile winder used to wind textile strands onto tubular support packages for further processing. The invention relates generally to textile strands such as yarns, filaments or tapes of natural or synthetic materials (all referred to as xe2x80x9cyarnsxe2x80x9d) and is particularly concerned with the traversing mechanism necessary for laying the yarn onto the package in a precise, regular pattern. The traditional mechanism for producing such traversing motion includes a grooved scroll or drum which either engages the yarn directly or drives a yarn guide, causing it move in a reciprocating, traversing motion. Such mechanisms are, however, limited in their speed of operation, are subject to mechanical wear, and must be replaced when changing the pattern by which the yarn is to be applied to the package.
Winders for which the invention is suitable include back-winders, rewinders and spoolers, among others. While the system is adaptable to new machines, the particular embodiment disclosed herein is explained by way of example with reference to a Leesona 861 rewinder to which the system has been retrofitted. The system is likewise adaptable to wind both straight-sided cylindrical and tapered packages.
Winding systems are as old as the mechanical processing of yarn. There are numerous types of winders for differing purposes. Recently developed methods of yarn production such as continuous filament extrusion and texturizing have further emphasized this demand for winders having higher speeds of operation. One form of traversing mechanism which has been proposed for operation at such high speeds includes slot-like yarn guides mounted on closely spaced driving members moving in opposite directions across the traverse so that the yarn is carried from one end of the traverse to the other by a guide of one member and is then transferred to a guide of the other member so as to be carried back in opposite direction. This avoids the problem arising from the inertia of the yarn guides or other parts being caused to move first in one direction and then the other with a very abrupt reversal at the end of each traverse. The transfer of the yarn from one guide to another presents its own problems and proposals have been made to include a deflector arrangement at each end of the field of traverse for assisting the transfer of the yarn from one guide to the other. Such traversing mechanisms must be used in conjunction with a package support roller on the winder so that the yarn passes from the yarn guide to a nip between the package and the support roller and is thus maintained under control over this part of its travel.
Other mechanical solutions have been proposed, but all contain inherent limitations arising out of the use of fixed design and machined parts specific to a particular wind.
There are several basic parameters which determine the pattern by which the yarn is applied to the package. These are the wind ratio, traverse length and gain. The wind ratio refers to the number of rotations of the spindle on which the yarn package is positioned for each back-and-forth passage of the yarn traverse. For example, a wind ratio of 6 means that approximately six winds are placed on the package during each back-and-forth passage of the yarn traverse along the length of the package, i.e, three in each direction. Traverse length refers to the length along the spindle of the yarn applied to the package. The xe2x80x9cgainxe2x80x9d refers to the minute amount of incremental progression in the placement of the yarn on the package during each traverse to prevent successive wraps of yarn from being placed directly on top of the previous wraps of yarn.
These parameters are well understood in the art. Moreover, efforts have been made to adapt these concepts to electronic systems. For example, the Vander Groef U.S. Pat. No. 5,499,775 Patent discloses a winder for winding a wire cable with a programmable traverse control. The system takes into account the unique problems of winding wire which is subject to kinking and twisting. A xe2x80x9cfigure 8xe2x80x9d package is produced which forms a xe2x80x9cholexe2x80x9d at a point where no cross-overs occur during the wire winding process. The stroke of the traverse is slightly out phase with the rotation of the wire spool so that the cross-overs progress around the spool. The number of cross-overs never advances a full 360 degrees around the spindle. Thus, the radial xe2x80x9cholexe2x80x9d is formed at the point where no cross-overs are made. The machine is operated by conventional motors.
The present system provides an electronic means of winding textile yarns which permits the various parameters to be controlled by software instead of by hardware. Thus, changes in wind ratios and traverse length can be made by changing the inputs into the system. In addition, a very efficient and effective traverse mechanism is provided capable of operating at the high speeds made possible by the electronic control of the winding process.
Therefore, it is an object of the invention to provide a winder which utilizes a programmable electronic controller to control various input parameters.
It is another object of the invention to provide a winder which uses a servo-motor to reciprocate a mechanical traverse mechanism efficiently and at high speed.
It is another object of the invention to provide a winder which uses a cable with a helical driving surface to move the traverse at high speed.
It is another object of the invention to provide a winder which utilizes a servo system which both runs the traverse motor and also executes the motion control application which defines the traverse parameters.
It is another object of the invention to provide a winder which is suitable for being retrofitted to a wide variety of existing mechanically-operated winders.
It is another object of the invention to provide a winder which improves machine flexibility, speeds machine setup changes, reduces maintenance costs and reduces machine noise and parts wear.
These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing a winding machine for winding a strand onto a tubular support to form a strand package, and comprising a spindle on which the tubular support is mounted for rotation therewith, a motor for rotating the spindle, and a reciprocating traverse mechanism, including a strand guide, for guiding the strand onto the tubular support at a predetermined traverse stroke and wind ratio. The traverse mechanism comprises a servo-motor for selectively starting and stopping reciprocating movement of the strand guide in accordance with the predetermined traverse stroke and wind ratio; and a programmable servo-controller for accepting data inputs reflecting the desired traverse stroke and wind ratio and for outputting data to the servo-motor reflecting the desired traverse stroke and wind ratio.
According to one preferred embodiment of the invention, the spindle is rotated at a constant strand winding speed. A speed sensor is provided for detecting the surface speed of the strand package. A spindle motor speed controller accepts a signal output from the speed sensor representing the surface speed of the strand package and outputs a signal representing the surface speed of the strand package. The signal is sent to the spindle motor speed controller for slowing the rpm of the spindle as the diameter of the strand package increases to maintain a constant spindle surface winding speed, and to the servo-controller for slowing the traverse servo-motor in synchronization with the slowing of the rpm of the strand package and thus maintaining a constant wind ratio.
According to another preferred embodiment of the invention, the traverse mechanism comprises a drive cable pulley carried by the servo-motor for rotation therewith, a driven cable pulley positioned in spaced-apart relation to the driven pulley, and a drive cable having first and second opposed ends attached to and carrying the strand guide. The drive cable extends around the drive cable pulley and driven cable pulley for being reciprocated by the starting and stopping reciprocating movement of the servo-motor under control of the servo-controller for moving the strand guide back-and-forth along the length of the spindle as the strand is wound onto the tubular support.
According to another preferred embodiment of the invention, said drive cable comprises a core member around which is wound a spiral member in a predetermined angle and spacing to define raised driving convolutions on the surface of the core. The drive cable pulley and said driven cable pulley are each provided with a plurality of regularly-spaced helical grooves on an outer peripheral driving surface thereof complementary with the driving convolutions on the surface of the core of the drive cable.
According to yet another preferred embodiment of the invention, the core member comprises a bundle of stranded stainless steel wire encapsulated in a flexible elastomeric jacket.
According to yet another preferred embodiment of the invention, said strand support is a constant diameter tube, and said strand comprises a textile yarn.
According to yet another preferred embodiment of the invention, said strand support is a cone, and said strand comprises a textile yarn.
According to yet another preferred embodiment of the invention, said winding machine comprises a machine selected from the group consisting of a rewinder, take-up winder, and two-for-one twister.
An embodiment of the method of winding a strand onto a tubular support to form a strand package according to the invention comprises the steps of providing a spindle on the which the tubular support is mounted for rotation therewith, a motor for rotating the spindle, and a reciprocating traverse mechanism, including a strand guide, for guiding the strand onto the tubular support at a predetermined traverse stroke and wind ratio. Data inputs are generated reflecting the desired predetermined traverse stroke and wind ratio. Data is output to a servo-motor driving the strand guide, said data reflecting the desired traverse stroke and wind ratio. The servo-motor is selectively started and stopped under the control of a servo-controller and thus the reciprocating movement of the strand guide in accordance with the predetermined stroke and wind ratio.
According to yet another preferred embodiment of the invention, the method includes the steps of rotating the spindle at a constant strand winding speed; detecting the surface speed of the strand package, and outputting a signal representing the surface speed of the strand package to a servo-controller. A signal is output representing the surface speed of the strand package for slowing the rpm of the spindle as the diameter of the strand package increases to maintaining a constant spindle surface speed, and to the servo-controller for slowing the traverse servo-motor in synchronization with the slowing of the rpm of the strand package and thus maintaining a constant wind ratio.
According to yet another preferred embodiment of the invention, the step of reciprocating the traverse mechanism comprises the steps of providing a drive cable pulley carried by the servo-motor for rotation therewith, providing a driven cable pulley positioned in spaced-apart relation to the driven pulley, and providing a drive cable having first and second opposed ends attached to and carrying the strand guide, said drive cable being passed around the drive cable pulley and driven cable pulley for being moved in opposite directions by the starting and stopping reciprocating movement of the servo-motor under control of the servo-controller for moving the strand guide back-and-forth along the length of the spindle as the strand is wound onto the tubular support.
According to yet another preferred embodiment of the invention, the drive cable comprises a core member around which is wound a spiral member in a precise predetermined angle and spacing to define raised driving convolutions on the surface of the core. The drive cable pulley and said driven cable pulley are each are provided with a plurality of regularly-spaced helical grooves on an outer peripheral driving surface thereof complementary to the raised driving convolutions on the drive cable.